• After a median follow-up of 18.9 months, the median PFS was 8.3 months in the sac-TMT group and 4.3 months in the chemotherapy group (hazard ratio (HR), 0.49; 95% confidence interval (CI), 0.39 to 0.62; two-sided P<0.0001).

• OS was significantly longer with sac-TMT than with chemotherapy (HR, 0.60; 95% CI, 0.44 to 0.82; two-sided P=0.001); 18-month OS rate was 65.8% and 48.0%, respectively. In the supplementary analysis, in which data were censored at the start date of subsequent ADC, the HR was 0.56 (95% CI, 0.41 to 0.77).

• Sac-TMT was associated with a higher incidence of stomatitis with most cases being mild and with grade 3 or higher cases reported in very few patients (4.8%; all were grade 3). Low incidence of ocular-surface toxic effects, no ILD or pneumonitis, and one infusion-related reaction (grade 2) was reported in the sac-TMT group.

On October 20, results from the Phase III registrational clinical study OptiTROP-Lung04—led by Professor Zhang Li's team from Sun Yat-sen University Cancer Center—were published in the New England Journal of Medicine (Impact Factor = 78.5). The study evaluated the efficacy and safety of the TROP2 antibody-drug conjugate (ADC) sacituzumab tirumotecan (sac-TMT) monotherapy versus pemetrexed plus platinum chemotherapy for the treatment of patients with epidermal growth factor receptor (EGFR)-mutant locally advanced or metastatic non-squamous non-small cell lung cancer (NSCLC) who have progressed failed after treatment with EGFR-tyrosine kinase inhibitor (TKI) therapy. The study was also selected as a Late-Breaking Abstract (LBA) at the 2025 European Society for Medical Oncology (ESMO) Congress and was presented as an oral report in the Presidential Symposium (Presentation # LBA5).  

OptiTROP-Lung04 is a randomized, open-label, multicenter Phase III study designed to evaluate the efficacy and safety of sac-TMT monotherapy versus pemetrexed plus platinum in patients with EGFR-mutated locally advanced or metastatic NSCLC who had progressed on prior EGFR-TKI therapy. Eligible patients were those with histologically and/or cytologically confirmed disease. The primary endpoint was Progression-Free Survival (PFS) assessed by a Blinded Independent Review Committee (BIRC) per RECIST v1.1, and the key secondary endpoint was overall survival (OS). Results showed that compared with platinum-based doublet chemotherapy, sac-TMT monotherapy demonstrated a statistically significant and clinically meaningful improvement in both PFS and OS. Consistent PFS and OS benefits were observed across all prespecified subgroups, including prior EGFR-TKI therapy, presence of liver or brain metastases, and EGFR mutation subtype.

Based on the positive results of the OptiTROP-Lung04 study, sac-TMT has been approved by the National Medical Products Administration (NMPA) in China for the treatment of adult patients with EGFR mutation-positive locally advanced or metastatic non-squamous NSCLC who have progressed after EGFR-TKI therapy. To date, sac-TMT monotherapy remains the only approved treatment option for advanced EGFR-mutant NSCLC patients who have progressed after prior TKI therapy, as well as those who have progressed after prior TKI and platinum-based chemotherapy (either concurrently or sequentially). This achievement provides comprehensive coverage for the entire population of TKI-resistant patients.

Dr. Michael Ge, Chief Ｅxecutive Officer of Kelun-Biotech, commented: “OptiTROP-Lung04 is a key study that propels sac-TMT from late-line to an earlier-line treatment-setting in lung cancer, achieving a significant improvement in overall survival. We are thrilled that the results have been published in The New England Journal of Medicine, allowing this important finding to be shared widely among medical professionals and providing a reference for future lung cancer research. Together with our partner MSD, we will continue to advance sac-TMT’s clinical development and regulatory approvals, covering broader lung cancer and other indications, with the goal of making sac-TMT a cornerstone therapy for the benefit of patients.”

Professor Shengxiang Ren from the Department of Oncology at Shanghai Pulmonary Hospital, Tongji University, stated: “The application of third-generation EGFR-TKIs has significantly improved the overall prognosis for patients with advanced EGFR-mutant NSCLC. However, drug resistance is almost inevitable. Traditional treatment after resistance involves platinum-based doublet chemotherapy, which offers limited overall benefit. In recent years, regimens of chemotherapy plus immune checkpoint inhibitors+anti-angiogenic agents, or EGFR/c-Met bsAb, or PD-1/VEGF bsAb, have been successively approved for this indication. However, all these approaches are chemotherapy-based, highlighting an urgent need to explore novel treatment regimens. The OptiTROP-Lung04 study confirms sac-TMT as the first treatment option as a monotherapy to deliver clear dual benefits in both PFS and OS following EGFR-TKI progression. The sequential application of sac-TMT prior to chemotherapy demonstrates strong competence, establishing itself as a new standard of care for patients with advanced EGFR-mutant lung cancer after TKI resistance.”

About Sac-TMT

Sac-TMT, a core product of the Company, is a novel human TROP2 ADC in which the Company has proprietary intellectual property rights, targeting advanced solid tumors such as NSCLC, breast cancer (BC), gastric cancer (GC), gynecological tumors, among others. Sac-TMT is developed with a novel linker to conjugate the payload, a belotecan-derivative topoisomerase I inhibitor with a drug-to-antibody-ratio (DAR) of 7.4. Sac-TMT specifically recognizes TROP2 on the surface of tumor cells by recombinant anti-TROP2 humanized monoclonal antibodies, which is then endocytosed by tumor cells and releases the payload KL610023 intracellularly. KL610023, as a topoisomerase I inhibitor, induces DNA damage to tumor cells, which in turn leads to cell-cycle arrest and apoptosis. In addition, it also releases KL610023 in the tumor microenvironment. Given that KL610023 is membrane permeable, it can enable a bystander effect, or in other words kill adjacent tumor cells.

In May 2022, the Company licensed the exclusive rights to MSD (the tradename of Merck & Co., Inc., Rahway, NJ, USA) to develop, use, manufacture and commercialize sac-TMT in all territories outside of Greater China (includes Mainland China, Hong Kong, Macau, and Taiwan).

To date, three indications for sac-TMT have been approved and marketed in China for the treatment of adult patients with unresectable locally advanced or metastatic triple negative breast cancer (TNBC) who have received at least two prior systemic therapies (at least one of them for advanced or metastatic setting), EGFR mutation-positive locally advanced or metastatic non-squamous NSCLC following progression on EGFR-TKI therapy and platinum-based chemotherapy and EGFR mutant-positive locally advanced or metastatic non-squamous NSCLC who progressed after treatment with EGFR-TKI therapy. Sac-TMT is the first TROP2 ADC drug approved for marketing in lung cancer globally. In addition, the new indication application for sac-TMT for the treatment of adult patients with unresectable locally advanced, metastatic hormone receptor positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) BC who have received prior endocrine therapy and other systemic treatments in the advanced or metastatic setting was accepted by the Center for Drug Evaluation of the NMPA, and was included in the priority review and approval process.

As of today, the Company has initiated 9 registrational clinical studies in China. MSD has initiated 15 ongoing Phase Ⅲ global clinical studies of sac-TMT as a monotherapy or with pembrolizumab1 or other anti-cancer agents for several types of cancer. These studies are sponsored and led by MSD.

About Kelun-Biotech

Kelun-Biotech (6990.HK) is a holding subsidiary of Kelun Pharmaceutical (002422.SZ), which focuses on the R&D, manufacturing, commercialization and global collaboration of innovative biological drugs and small molecule drugs. The company focuses on major disease areas such as solid tumors, autoimmune, inflammatory, and metabolic diseases, and in establishing a globalized drug development and industrialization platform to address the unmet medical needs in China and the rest of world. The Company is committed to becoming a leading global enterprise in the field of innovative drugs. At present, the Company has more than 30 ongoing key innovative drug projects, of which 4 projects have been approved for marketing, 1 project is in the NDA stage and more than 10 projects are in the clinical stage. The company has established one of the world's leading proprietary ADC and novel DC platforms, OptiDC™, and has 2 ADC projects approved for marketing, and multiple ADC and novel DC assets in clinical or preclinical research stage. For more information, please visit https://kelun-biotech.com/.

References:

1. Pembrolizumab (KEYTRUDA®) is a registered trademark of Merck Sharp & Dohme LLC (MSD), a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.

CHENGDU, China, Oct, 18 , 2025——Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. (the “Company”) announced that at the 2025 European Society for Medical Oncology (ESMO) Congress held in Berlin, Germany, Results from a Phase 3 study of the Company’s human epidermal growth factor receptor 2 (HER2)-directed ADC trastuzumab botidotin (also known as A166) trastuzumab botidotin versus trastuzumab emtansine (T-DM1) in HER2-positive unresectable or metastatic BC was presented as an oral report by Professor Xichun Hu from Fudan University Shanghai Cancer Center (Presentation # LBA24, Proffered paper session 1: Breast cancer, metastatic).

Trastuzumab botidotin is a HER2-targeted ADC composed of a cytotoxic drug (Duostatin-5, anti-microtubule agent) with site-specific conjugation to trastuzumab via a stable protease-cleavable valine-citrulline linker. The unique linker is stable in plasma and selectively cleaved by lysosomal cathepsin B that is up-regulated in cancer cells.

In this study, a total of 365 patients with HER2+ unresectable or metastatic BC who had received at least one prior anti-HER2 therapy were randomized (1:1) to receive trastuzumab botidotin or T-DM1. 53% of patients had received ≥2 lines of anti-HER2 therapy, 61% of patients had HER2 Immunohistochemistry (IHC) 3+, and 60% of patients had been treated with TKIs, particularly pyrotinib (56%). As of April 26, 2025, median follow-up was 14.9 months.

Median PFS was significantly longer in trastuzumab botidotin than in T-DM1 (11.1 months vs 4.4 months; HR: 0.39, 95% CI, 0.30-0.51, p<0.0001). PFS benefit with trastuzumab botidotin was consistently observed regardless of prior lines of anti-HER2 therapy (HR 0.36, 95% CI, 0.25-0.53, for 1 prior line; HR 0.39, 95% CI, 0.28-0.56, for ≥2 prior lines).

ORR by blinded independent central review (BICR) was 76.9% vs 53.0%.

A trend toward benefit in OS was observed in trastuzumab botidotin (HR 0.62; 95% CI, 0.38-1.03).

Grade ≥3 treatment emergent adverse events (TEAEs) occurred in 69.8% of patients in trastuzumab botidotin and 63.7% in T-DM1. The most common TEAEs associated with dose reduction were ocular AEs for trastuzumab botidotin, and were platelet count decreased for trastuzumab emtansine. Only two patients permanently discontinued trastuzumab botidotin due to TEAE. No on-treatment deaths were observed in trastuzumab botidotin, compared with 1.6% in T-DM1, all of which were considered unrelated to treatment.

As a conclusion, this second head-to-head trial comparing T-DM1 with other anti-HER2 regimens demonstrated that trastuzumab botidotin statistically improved PFS with an ORR of 76.9% vs 53.0%. PFS benefit with trastuzumab botidotin was consistently observed regardless of prior lines of anti-HER2 therapy. Ocular AEs were also manageable.

"Professor Xichun Hu, National Lead Principal Investigator from Fudan University Shanghai Cancer Center:“Trastuzumab botidotin effectively balances safety and efficacy through its unique molecular design, reducing the incidence of interstitial lung disease and hematologic toxicity. According to research data, trastuzumab botidotin demonstrated significant survival benefits in the pivotal Phase III trial, with an overall manageable safety profile, providing a new important treatment option for pretreated HER2+ BC patients. These positive results also offer robust evidence-based support for personalized treatment and updates to clinical practice guidelines.”

About Trastuzumab botidotin

Trastuzumab botidotin is a differentiated HER2 ADC to treat advanced HER2+ solid tumors. As an innovative HER2 ADC developed by the Company, it conjugates a novel, monomethyl auristatin F (MMAF) derivative (a highly cytotoxic tubulin inhibitor, Duo-5) via a stable, enzyme-cleavable linker to a HER2 monoclonal antibody with a DAR of 2. Trastuzumab botidotin specifically binds to HER2 on the surface of tumor cells and is internalized by tumor cells, releasing the toxin molecule Duo-5 inside the cell. Duo-5 induces tumor cell cycle arrest in the G2/M phase, leading to tumor cell apoptosis. After targeting HER2, trastuzumab botidotin can also inhibit the HER2 signaling pathway; it has antibody-dependent cell-mediated cytotoxicity (ADCC) activity.

Based on the results of a multi-center, randomized, open-label, controlled, Phase 3 KL166-III-06 study, trastuzumab botidotin was approved for marketing by the NMPA in for adult patients with unresectable or metastatic HER2 positive BC who have received one or more prior anti-HER2 therapy. At a pre-specified interim analysis, trastuzumab botidotin demonstrated a statistically significant and clinically meaningful improvement in the primary endpoint of PFS as assessed by the BICR compared with T-DM1[; the beneficial trend for OS of trastuzumab botidotin was also observed.

Currently, the Company has initiated an open, multi-center Phase 2 clinical study of trastuzumab botidotin in the treatment of HER2+ unresectable or metastatic BC that previously received a topoisomerase inhibitor ADC.

About Kelun-Biotech

Kelun-Biotech (6990.HK) is a holding subsidiary of Kelun Pharmaceutical (002422.SZ), which focuses on the R&D, manufacturing, commercialization and global collaboration of innovative biological drugs and small molecule drugs. The company focuses on major disease areas such as solid tumors, autoimmune, inflammatory, and metabolic diseases, and in establishing a globalized drug development and industrialization platform to address the unmet medical needs in China and the rest of world. The Company is committed to becoming a leading global enterprise in the field of innovative drugs. At present, the Company has more than 30 ongoing key innovative drug projects, of which 4 projects have been approved for marketing, 1 projects are in the NDA stage and more than 10 projects are in the clinical stage. The company has established one of the world's leading proprietary ADC and novel DC platforms, OptiDC™, and has 1 ADC project approved for marketing and multiple ADC and novel DC assets in clinical or preclinical research stage. For more information, please visit https://kelun-biotech.com/.

CHENGDU, China, Oct, 19, 2025——Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. (the “Company”) announced that at the 2025 European Society for Medical Oncology (ESMO) Congress held in Berlin, Germany, results from a Phase 3 OptiTROP-Lung04 trial of the Company’s trophoblast cell-surface antigen 2 (TROP2)-directed antibody-drug conjugate (ADC) sacituzumab tirumotecan (sac-TMT)  in EGFR-mutated non-small cell lung cancer (NSCLC) following progression on epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) was presented as an oral report by Professor Li Zhang from Sun Yat-sen University Cancer Center (Presentation # LBA5, Presidential Symposium II) and were simultaneously published in the New England Journal of Medicine (Impact Factor = 78.5).

In the OptiTROP-Lung04 trial, a total of 376 patients were randomized (1:1) to receive sac-TMT monotherapy or chemotherapy.

As at the data cut-off date July 06, 2025, the median follow-up is 18.9 months. the median Progression-Free Survival (PFS) was 8.3 months in the sac-TMT group and 4.3 months in the chemotherapy group. Sac-TMT significantly improved PFS over chemotherapy with 51% lower risk of disease progression or death (hazard ratio (HR) 0.49; 95% confidence interval (CI), 0.39-0.62; P<0.0001).

At the preplanned interim analysis of overall survival (OS), the OS was not reached (NR) in the sac-TMT group and 17.4 months in the chemotherapy group. sac-TMT significantly improved OS over chemotherapy with 40% lower risk of death (hazard ratio (HR) 0.6; 95% CI: 0.44-0.82; two-sided P=0.001). In the supplemental analysis, when censoring patients at the date of initiation of subsequent ADCs, sac-TMT significantly improved OS over chemotherapy with 44% lower risk of death (HR, 0.56; 95% CI, 0.41 - 0.77).

Sac-TMT significantly improved ORR as compared to chemotherapy (60.6% vs 43.1%)

A consistent PFS and OS benefit of sac-TMT over chemotherapy was observed across all predefined subgroups, including prior EGFR-TKI therapy, presence of liver or brain metastases, and EGFR mutation subtype.

The incidence of any grade treatment-related adverse events (TRAEs) and grade ≥3 TRAEs was similar between the two groups. The most common TRAEs for both sac-TMT and chemotherapy were hematologic toxicities. No TRAEs led to discontinuation or death, and no cases of interstitial lung disease/pneumonitis were reported in the sac-TMT group. Ocular surface toxicity: occurred in 9.6% of patients in the sac-TMT group, all of which were grade 1 - 2.

As a conclusion, sac-TMT demonstrates highly statistically significant and clinically meaningful improvements in PFS and OS compared to platinum-based chemotherapy and showed a manageable safety profile, with no unexpected safety signals identified. Several global phase 3 studies of sac-TMT monotherapy (NCT06305754, NCT06074588) and combination study with osimertinib in China (NCT06670196) in EGFR-mutant NSCLC are ongoing.

Professor Zhang Li, National Lead Principal Investigator from Sun Yat-sen University Cancer Center, commented: "Compared to platinum-based doublet chemotherapy, sac-TMT not only significantly prolonged PFS but also demonstrated a statistically significant and clinically meaningful improvement in OS within this patient population. This achievement marks a major breakthrough in global lung cancer treatment—sac-TMT, as a monotherapy, demonstrated statistically significant and clinically meaningful improvements in both PFS and OS in the Phase III trial for patients with EGFR-TKI-resistant NSCLC. This study provides highly valuable, new evidence-based guidance for lung cancer management worldwide and has the potential to reshape the therapeutic landscape for EGFR-TKI-resistant NSCLC "

 About sac-TMT

Sac-TMT, a core product of the Company, is a novel human TROP2 ADC in which the Company has proprietary intellectual property rights, targeting advanced solid tumors such as NSCLC, BC, GC, gynecological tumors, among others. Sac-TMT is developed with a novel linker to conjugate the payload, a belotecan-derivative topoisomerase I inhibitor with a drug-to-antibody-ratio (DAR) of 7.4. Sac-TMT specifically recognizes TROP2 on the surface of tumor cells by recombinant anti-TROP2 humanized monoclonal antibodies, which is then endocytosed by tumor cells and releases the payload KL610023 intracellularly. KL610023, as a topoisomerase I inhibitor, induces DNA damage to tumor cells, which in turn leads to cell-cycle arrest and apoptosis. In addition, it also releases KL610023 in the tumor microenvironment. Given that KL610023 is membrane permeable, it can enable a bystander effect, or in other words kill adjacent tumor cells.

In May 2022, the Company licensed the exclusive rights to MSD (the tradename of Merck & Co., Inc, Rahway, NJ, USA) to develop, use, manufacture and commercialize sac-TMT in all territories outside of Greater China (which includes Mainland China, Hong Kong, Macao and Taiwan).

To date, three indications for sac-TMT have been approved and marketed in China for the treatment of adult patients with unresectable locally advanced or metastatic triple negative breast cancer (TNBC) who have received at least two prior systemic therapies (at least one of them for advanced or metastatic setting), EGFR mutation-positive locally advanced or metastatic non-squamous NSCLC following progression on EGFR-TKI therapy and platinum-based chemotherapy and EGFR mutant-positive locally advanced or metastatic non-squamous NSCLC who progressed after treatment with EGFR-TKI therapy. Sac-TMT is the first TROP2 ADC drug approved for marketing in lung cancer globally. In addition, the new indication applications for sac-TMT for the treatment of adult patients with unresectable locally advanced, metastatic HR+/HER2- BC who have received prior endocrine therapy and other systemic treatments in the advanced or metastatic setting was accepted by the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA), and was included in the priority review and approval process.

As of today, the Company has initiated 9 registrational clinical studies in China. MSD has initiated 15 ongoing Phase 3 global clinical studies of sac-TMT as a monotherapy or with pembrolizumab or other anti-cancer agents for several types of cancer. These studies are sponsored and led by MSD.

About Kelun-Biotech

Kelun-Biotech (6990.HK) is a holding subsidiary of Kelun Pharmaceutical (002422.SZ), which focuses on the R&D, manufacturing, commercialization and global collaboration of innovative biological drugs and small molecule drugs. The company focuses on major disease areas such as solid tumors, autoimmune, inflammatory, and metabolic diseases, and in establishing a globalized drug development and industrialization platform to address the unmet medical needs in China and the rest of world. The Company is committed to becoming a leading global enterprise in the field of innovative drugs. At present, the Company has more than 30 ongoing key innovative drug projects, of which 4 projects have been approved for marketing, 1 project is in the NDA stage and more than 10 projects are in the clinical stage. The company has established one of the world's leading proprietary ADC and novel DC platforms, OptiDC™, and has 2 ADC project approved for marketing and multiple ADC and novel DC assets in clinical or preclinical research stage. For more information, please visit https://kelun-biotech.com/.

CHENGDU, China, Oct, 18 , 2025——Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. (the “Company”) announced that at the 2025 European Society for Medical Oncology (ESMO) Congress held in Berlin, Germany, results from a Phase 3 OptiTROP-Breast02 study of the Company’s trophoblast cell-surface antigen 2 (TROP2)-directed antibody-drug conjugate (ADC) sacituzumab tirumotecan (sac-TMT) (佳泰莱®) in previously treated locally advanced or metastatic hormone receptor-positive (HR+) and human epidermal growth factor receptor 2 -negative (HER2-) breast cancer (BC) was presented as an oral report by Professor Man Li from the Second Affiliated Hospital of Dalian Medical University (Presentation # LBA23, Proffered paper session 1: Breast cancer, metastatic). Previously, the new indication applications for sac-TMT for this indication was accepted by the National Medical Products Administration (NMPA) and was included in the priority review and approval process.

In the OptiTROP-Breast02 study, a total of 399 patients with HR+/HER2- BC who had progression on CDK4/6 inhibitors and received at least one prior line of chemotherapy in the advanced/metastatic setting were randomized (1:1) to receive sac-TMT or investigator's choice of chemotherapy (ICC).

As at the data cut-off date January 22, 2025, the median PFS was significantly longer in sac-TMT than in ICC (8.3 vs. 4.1 months; HR, 0.35; 95% CI, 0.26-0.48; P<0.0001). Clinical benefit was seen in sac-TMT independent of HER2 expression (HR for PFS in HER2-zero: 0.39, 95% CI, 0.26-0.57; in HER2-low: 0.31, 95% CI, 0.20-0.48).

Sac-TMT showed longer DoR versus chemotherapy; and ORR was also superior with sac-TMT to ICC.

There was a trend in OS that favored sac-TMT over ICC (HR, 0.33; 95% CI, 0.18-0.61).

Grade ≥ 3 TRAEs occurred in 62.0% and 64.8% of patients in sac-TMT and ICC. TRAE led to discontinuation in 0% and 0.5% of patients; pneumonitis occurred in 1.5% and 1.0% of patients (all grade 1-2) in sac-TMT and ICC, respectively.

As a conclusion, sac-TMT demonstrated statistically significant and clinically meaningful improvement in PFS compared to chemotherapy. PFS benefit was observed across all predefined subgroups and independent of HER2 status. Sac-TMT also showed a trend toward OS benefit (HR, 0.33; 95% CI, 0.18, 0.61) and demonstrated a favorable and manageable safety profile, with no new safety signals. Currently, a Phase III clinical study of sacituzumab tirumotecan as monotherapy and in combination with pembrolizumab in patients with chemotherapy-naïve HR+/HER2- breast cancer is ongoing globally, with a planned enrollment of approximately 1,200 participants. Additionally, another Phase III registrational study in the same population is currently enrolling patients in China, with a planned enrollment of 430 participants.

Professor Man Li from the Second Affiliated Hospital of Dalian Medical University, stated：“The Phase III OptiTROP-Breast02 study confirmed that, regardless of HER2 expression status, sac-TMT demonstrated promising efficacy in previously treated HR+/HER2- BC patients. As the first Phase III clinical trial focusing exclusively on an all-Chinese population with HR+/HER2- BC, the presentation of the OptiTROP-Breast02 study data at ESMO marks a significant breakthrough in clinical research in this indications in China. The positive outcomes of this study not only provide evidence-based support for the treatment of HR+/HER2- BC but also offer a safe and reliable new treatment option for breast cancer patients.”

About sac-TMT (佳泰莱®)

Sac-TMT, a core product of the Company, is a novel human TROP2 ADC in which the Company has proprietary intellectual property rights, targeting advanced solid tumors such as NSCLC, BC, GC, gynecological tumors, among others. Sac-TMT is developed with a novel linker to conjugate the payload, a belotecan-derivative topoisomerase I inhibitor with a drug-to-antibody-ratio (DAR) of 7.4. Sac-TMT specifically recognizes TROP2 on the surface of tumor cells by recombinant anti-TROP2 humanized monoclonal antibodies, which is then endocytosed by tumor cells and releases the payload KL610023 intracellularly. KL610023, as a topoisomerase I inhibitor, induces DNA damage to tumor cells, which in turn leads to cell-cycle arrest and apoptosis. In addition, it also releases KL610023 in the tumor microenvironment. Given that KL610023 is membrane permeable, it can enable a bystander effect, or in other words kill adjacent tumor cells.

In May 2022, the Company licensed the exclusive rights to MSD (the tradename of Merck & Co., Inc, Rahway, NJ, USA) to develop, use, manufacture and commercialize sac-TMT in all territories outside of Greater China (which includes Mainland China, Hong Kong, Macao and Taiwan).

To date, three indications for sac-TMT have been approved and marketed in China for the treatment of adult patients with unresectable locally advanced or metastatic triple negative breast cancer (TNBC) who have received at least two prior systemic therapies (at least one of them for advanced or metastatic setting), EGFR mutation-positive locally advanced or metastatic non-squamous NSCLC following progression on EGFR-TKI therapy and platinum-based chemotherapy and EGFR mutant-positive locally advanced or metastatic non-squamous NSCLC who progressed after treatment with EGFR-TKI therapy. Sac-TMT is the first TROP2 ADC drug approved for marketing in lung cancer globally. In addition, the new indication applications for sac-TMT for the treatment of adult patients with unresectable locally advanced, metastatic HR+/HER2- BC who have received prior endocrine therapy and other systemic treatments in the advanced or metastatic setting was accepted by the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA), and was included in the priority review and approval process.

As of today, the Company has initiated 9 registrational clinical studies in China. MSD has initiated 15 ongoing Phase 3 global clinical studies of sac-TMT as a monotherapy or with pembrolizumab or other anti-cancer agents for several types of cancer. These studies are sponsored and led by MSD.

About Kelun-Biotech

Kelun-Biotech (6990.HK) is a holding subsidiary of Kelun Pharmaceutical (002422.SZ), which focuses on the R&D, manufacturing, commercialization and global collaboration of innovative biological drugs and small molecule drugs. The company focuses on major disease areas such as solid tumors, autoimmune, inflammatory, and metabolic diseases, and in establishing a globalized drug development and industrialization platform to address the unmet medical needs in China and the rest of world. The Company is committed to becoming a leading global enterprise in the field of innovative drugs. At present, the Company has more than 30 ongoing key innovative drug projects, of which 4 projects have been approved for marketing, 1 project is in the NDA stage and more than 10 projects are in the clinical stage. The company has established one of the world's leading proprietary ADC and novel DC platforms, OptiDC™, and has 2 ADC project approved for marketing and multiple ADC and novel DC assets in clinical or preclinical research stage. For more information, please visit https://kelun-biotech.com/.

CHENGDU, China, Oct, 17 , 2025——Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. (the “Company”) announced that the Company’s human epidermal growth factor receptor 2 (HER2)-directed antibody-drug conjugate (ADC) trastuzumab botidotin (also known as A166) (舒泰莱®) was approved for marketing by the National Medical Products Administration (NMPA) for the treatment of adult patients with unresectable or metastatic HER2-positive breast cancer (BC) who have received one or more prior anti-HER2 therapy.

The approval is based on a multi-center, randomized, open-label, controlled, Phase 3 KL166-III-06 study that evaluates the efficacy and safety profile of trastuzumab botidotin versus T-DM1 in patients with HER2-positive unresectable or metastatic BC who have received prior trastuzumab and taxane-containing regimens. At a pre-specified interim analysis, trastuzumab botidotin monotherapy demonstrated a statistically significant and clinically meaningful improvement in the primary endpoint of progression-free survival (PFS) as assessed by the blinded independent central review (BICR) compared with T-DM1; the beneficial trend for overall survival (OS) of trastuzumab botidotin was also observed. Results from this study will be presented as an oral report at the 2025 European Society for Medical Oncology (ESMO) Congress held in Berlin, Germany (Presentation # LBA24, Proffered paper session 1: Breast cancer, metastatic).

The Company has initiated an open, multi-center Phase 2 clinical study of trastuzumab botidotin in the treatment of HER2+ unresectable or metastatic BC that previously received a topoisomerase inhibitor ADC.

Dr. Michael Ge, CEO of Kelun-Biotech said, “We are thrilled to see our first HER2 ADC drug, trastuzumab botidotin, successfully approved for market. This marks a significant advancement in the treatment of HER2-positive breast cancer. As China's first domestically developed HER2 ADC capable of broadly covering 2L+ HER2 BC patients, trastuzumab botidotin leverages its differentiated structural design to deliver superior efficacy while addressing unmet clinical needs in this population."

About HER2+ BC

Breast cancer, as the most common malignant tumor, poses a serious threat to women's health. Among its subtypes, HER2-positive breast cancer accounts for approximately 15%–20% of all breast cancer cases[1], and is characterized by its aggressiveness and high malignancy. According to the 2025 CSCO guidelines, first-line treatment for HER2-positive breast cancer primarily consists of trastuzumab and pertuzumab in combination with taxane-based chemotherapeutic agents. Second-line treatment regimens comprise tyrosine kinase inhibitors (TKIs, such as pyrotinib) and antibody-drug conjugates (ADCs, such as T-DM1 and T-DXd). Following disease progression on second-line therapy, subsequent treatment strategies are determined based on prior second-line regimens, the patient’s tolerance to therapy, tumor burden, and other relevant factors. Despite recent advances in anti-HER2 therapeutics, a significant number of patients still experience drug resistance or severe adverse effects, highlighting an urgent need for agents with improved safety profiles to address the treatment requirements of patients with recurrent or drug-resistant HER2-positive breast cancer.

About trastuzumab botidotin (舒泰莱®)

Trastuzumab botidotin is a differentiated HER2 ADC to treat advanced HER2+ solid tumors. As an innovative HER2 ADC developed by the Company, it conjugates a novel, monomethyl auristatin F (MMAF) derivative (a highly cytotoxic tubulin inhibitor, Duo-5) via a stable, enzyme-cleavable linker to a HER2 monoclonal antibody with a drug-to-antibody-ratio (DAR) of 2. Trastuzumab botidotin specifically binds to HER2 on the surface of tumor cells and is internalized by tumor cells, releasing the toxin molecule Duo-5 inside the cell. Duo-5 induces tumor cell cycle arrest in the G2/M phase, leading to tumor cell apoptosis. After targeting HER2, trastuzumab botidotin can also inhibit the HER2 signaling pathway; it has antibody-dependent cell-mediated cytotoxicity (ADCC) activity.

About Kelun-Biotech

Kelun-Biotech (6990.HK) is a holding subsidiary of Kelun Pharmaceutical (002422.SZ), which focuses on the R&D, manufacturing, commercialization and global collaboration of innovative biological drugs and small molecule drugs. The company focuses on major disease areas such as solid tumors, autoimmune, inflammatory, and metabolic diseases, and in establishing a globalized drug development and industrialization platform to address the unmet medical needs in China and the rest of world. The Company is committed to becoming a leading global enterprise in the field of innovative drugs. At present, the Company has more than 30 ongoing key innovative drug projects, of which 4 projects have been approved for marketing, and more than 10 projects are in the clinical stage. The company has established one of the world's leading proprietary ADC and novel DC platforms, OptiDC™, and has 2 ADC projects approved for marketing, and multiple ADC and novel DC assets in clinical or preclinical research stage. For more information, please visit https://kelun-biotech.com/

Reference:

[1]. CRONIN K A, HARLAN L C, DODD K W, et al. Population-based estimate of the prevalence of HER2-positive breast cancer tumors for early stage patients in the US [J]. Cancer Invest,2010, 28(9): 963-968. DOI: 10.3109/07357907.2010.496759.

CHENGDU, China, October, 11, 2025—Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. (the “Company”) announced that the Company’s trophoblast cell-surface antigen 2 (TROP2)-directed antibody-drug conjugate (ADC) sacituzumab tirumotecan (sac-TMT, also known as SKB264/MK-2870) was approved for marketing by the National Medical Products Administration (NMPA) for its third indication, the treatment of adult patients with epidermal growth factor receptor (EGFR) mutant-positive locally advanced or metastatic non-squamous non-small cell lung cancer (NSCLC) who progressed after treatment with EGFR-tyrosine kinase inhibitor (TKI) therapy.

Sac-TMT is the first and only ADC globally to show an overall survival (OS) benefit compared with platinum doublet chemotherapy and be approved for advanced NSCLC that has progressed after only TKI therapy (second line). Currently sac-TMT monotherapy is the only regimen approved for advanced EGFR-mutant NSCLC following progression on TKI therapy or TKI therapy and platinum-based chemotherapy (used sequentially or in combination)—achieving comprehensive coverage across the TKI-resistant population.

In a pre-specified interim analysis of OS, compared with the current standard of care of platinum-based doublet chemotherapy, sac-TMT monotherapy demonstrated a statistically significant and clinically meaningful improvement in both progression-free survival (PFS) and OS, and significantly extends survival outcomes for these patients. More importantly, it remains the only monotherapy regimen not based on platinum-based doublet chemotherapy approved for NSCLC following progression after TKI therapy.

The approval is based on a randomized, open-label, multi-center Phase III study (OptiTROP-Lung04) which has been selected as a late-breaking abstract (LBA) at the 2025 European Society for Medical Oncology (ESMO) Congress and will be presented as an oral report in the Presidential Symposium session (Presentation # LBA5). The OptiTROP-Lung04 study evaluates the efficacy and safety profile of sac-TMT monotherapy at 5mg/kg every other week (Q2W) as an intravenous injection versus pemetrexed plus platinum chemotherapy for the treatment of patients with EGFR-mutant locally advanced or metastatic non-squamous NSCLC who have failed after treatment with EGFR-TKI therapy. This is the first Phase III trial globally in a Chinese population demonstrating significant OS improvement with an ADC compared to platinum-based doublet chemotherapy in EGFR-mutant NSCLC following TKI-resistance. Sac-TMT demonstrated statistically significant and clinically meaningful improvement in both OS and PFS.

In March 2025, sac-TMT was approved for EGFR mutant-positive locally advanced or metastatic non-squamous NSCLC following progression on EGFR-TKI therapy and platinum-based chemotherapy. Compared with current standard of care of docetaxel, sac-TMT monotherapy significantly extends the PFS and OS for these patients. Additionally, the patient enrollment for a Phase III registrational study in China of sac-TMT combined with osimertinib as first-line treatment of locally advanced or metastatic non-squamous EGFR-mutant NSCLC has been completed.

Dr. Michael Ge, CEO of Kelun-Biotech said, “We are delighted to announce the approval of the third indication for our core product, sac-TMT, marking another major milestone in lung cancer treatment. EGFR mutations are the most common oncogenic driver in lung cancer, accounting for approximately 40–50% of non-squamous NSCLC cases in China. Third-generation EGFR-TKIs are the standard first-line therapy for these patients, yet resistance inevitably develops, leaving few effective treatment options. The approval of this new indication highlights sac-TMT’s broad coverage across TKI-treated NSCLC, offering a more precise and effective treatment with a proven survival benefit for a larger patient population. Looking ahead, we are advancing the clinical development of sac-TMT in combination with osimertinib for first-line EGFR-mutant NSCLC.”

About NSCLC

Lung cancer is the leading malignant tumor in China. According to statistics from the National Cancer Center, approximately 1.06 million1 new lung cancer cases are diagnosed annually in the country. Pathological classification of lung cancer primarily includes non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC), with NSCLC being the most common pathological type, accounting for about 80–85% of all lung cancer patients. According to the 2025 Chinese Society of Clinical Oncology (CSCO) Guidelines for Diagnosis and Treatment of Non-Small Cell Lung Cancer and the Chinese Medical Association Guidelines for Clinical Diagnosis and Treatment of Lung Cancer (2025 Edition), EGFR-TKI therapy is the first-line treatment for advanced NSCLC with EGFR mutations2,3. Following resistance to EGFR-TKIs, platinum-based doublet chemotherapy remains the primary standard treatment regimen. Current treatment options demonstrate suboptimal efficacy, particularly in extending overall survival, leaving significant unmet clinical needs where there’s urgent requirement for new drugs to improve patient survival outcomes.

About Sac-TMT

Sac-TMT, a core product of the Company, is a novel human TROP2 ADC in which the Company has proprietary intellectual property rights, targeting advanced solid tumors such as NSCLC, breast cancer (BC), gastric cancer (GC), gynecological tumors, among others. Sac-TMT is developed with a novel linker to conjugate the payload, a belotecan-derivative topoisomerase I inhibitor with a drug-to-antibody-ratio (DAR) of 7.4. Sac-TMT specifically recognizes TROP2 on the surface of tumor cells by recombinant anti-TROP2 humanized monoclonal antibodies, which is then endocytosed by tumor cells and releases the payload KL610023 intracellularly. KL610023, as a topoisomerase I inhibitor, induces DNA damage to tumor cells, which in turn leads to cell-cycle arrest and apoptosis. In addition, it also releases KL610023 in the tumor microenvironment. Given that KL610023 is membrane permeable, it can enable a bystander effect, or in other words kill adjacent tumor cells.

In May 2022, the Company licensed the exclusive rights to MSD (the tradename of Merck & Co., Inc., Rahway, NJ, USA) to develop, use, manufacture and commercialize sac-TMT in all territories outside of Greater China (includes Mainland China, Hong Kong, Macau, and Taiwan).

To date, three indications for sac-TMT have been approved and marketed in China for the treatment of adult patients with unresectable locally advanced or metastatic triple negative breast cancer (TNBC) who have received at least two prior systemic therapies (at least one of them for advanced or metastatic setting), EGFR mutation-positive locally advanced or metastatic non-squamous NSCLC following progression on EGFR-TKI therapy and platinum-based chemotherapy and EGFR mutant-positive locally advanced or metastatic non-squamous NSCLC who progressed after treatment with EGFR-TKI therapy. Sac-TMT is the first TROP2 ADC drug approved for marketing in lung cancer globally. In addition, the new indication application for sac-TMT for the treatment of adult patients with unresectable locally advanced, metastatic hormone receptor positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) BC who have received prior endocrine therapy and other systemic treatments in the advanced or metastatic setting was accepted by the Center for Drug Evaluation of the NMPA, and was included in the priority review and approval process.

As of today, the Company has initiated 9 registrational clinical studies in China. MSD has initiated 14 ongoing Phase 3 global clinical studies of sac-TMT as a monotherapy or with pembrolizumab4 or other anti-cancer agents for several types of cancer. These studies are sponsored and led by MSD.

About Kelun-Biotech

Kelun-Biotech (6990.HK) is a holding subsidiary of Kelun Pharmaceutical (002422.SZ), which focuses on the R&D, manufacturing, commercialization and global collaboration of innovative biological drugs and small molecule drugs. The company focuses on major disease areas such as solid tumors, autoimmune, inflammatory, and metabolic diseases, and in establishing a globalized drug development and industrialization platform to address the unmet medical needs in China and the rest of world. The Company is committed to becoming a leading global enterprise in the field of innovative drugs. At present, the Company has more than 30 ongoing key innovative drug projects, of which 3 projects have been approved for marketing, 2 projects are in the NDA stage and more than 10 projects are in the clinical stage. The company has established one of the world's leading proprietary ADC and novel DC platforms, OptiDC™, and has 1 ADC project approved for marketing, 1 ADC project in NDA stage and multiple ADC and novel DC assets in clinical or preclinical research stage. For more information, please visit https://kelun-biotech.com/.

References:

[1]. Analysis of the Epidemiology of Malignant Tumors in China in 2022 [J]. Chinese Journal of Oncology, 2024, 46(3):221-231.

[2]. Chinese Society of Clinical Oncology (CSCO) (2025). Diagnosis and Treatment Guidelines for Non-Small Cell Lung Cancer.

[3]. Chinese Medical Association Clinical Diagnosis and Treatment Guidelines for Lung Cancer (2025 Edition) [J]. Chinese Journal of Cancer, 2025, 47(9): 769-810.

[4]. Pembrolizumab (KEYTRUDA®) is a registered trademark of Merck Sharp & Dohme LLC (MSD), a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.

CHENGDU, China, Sept. 23, 2025 /PRNewswire/ -- The 2025 European Society for Medical Oncology (ESMO) Congress will take place in Berlin, Germany, from October 17 to 21. Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. ("Kelun-Biotech", HKEX: 6990) will present results from multiple clinical studies at the congress, including data from its TROP2 ADC sacituzumab tirumotecan (sac-TMT), HER2 ADC A166 (trastuzumab botidotin), and CLDN18.2 ADC SKB315. Among these, two Phase III clinical studies of sac-TMT were selected for the Latest Breakthrough Abstracts (LBA) and presented as oral reports, including one featured in the Presidential Symposium; one Phase III clinical study of A166 was selected for LBA and presented as oral report.

Abstract titles of these studies have been published on the official website of ESMO. The study results to be presented include:

Title: Sacituzumab tirumotecan (sac-TMT) vs platinum-based chemotherapy in EGFR-mutated (EGFRm) non-small cell lung cancer (NSCLC) following progression on EGFR-TKIs: results from the randomized, multi-center phase 3 OptiTROP-Lung04 study
Presentation Type: Presidential Symposium 
Presentation #: LBA5
Date and Lecture Time: October 19, 4：52 PM to 5:04 PM local time

Title: Sacituzumab tirumotecan (sac-TMT) vs investigator's choice of chemotherapy (ICC) in previously treated locally advanced or metastatic hormone receptor-positive, HER2-negative (HR+/HER2-) breast cancer (BC): results from the randomized, multi-center phase 3 OptiTROP-Breast02 study
Presentation Type: Proffered Paper
presentation #: LBA23
Date and Lecture Time: October 18, 10:45 AM to 10:55 AM local time

Title: Trastuzumab botidotin vs trastuzumab emtansine (T-DM1) in HER2-positive unresectable or metastatic breast cancer: results from a randomized phase 3 study
Presentation Type: Proffered Paper 
presentation #: LBA24
Date and Lecture Time: October 18, 10:55 AM to 11:05AM local time

Title: SKB315, a novel Claudin 18.2 (CLDN18.2) antibody-drug conjugate (ADC), in patients (pts) with advanced solid tumors including gastric/ gastroesophageal junction cancer (GC/GEJC): a phase 1 study
Presentation Type: Poster
Presentation #: 2139P
Date and Session Time: October 19, 9:00 AM to 5:00 PM local time

Title: Sacituzumab tirumotecan (sac-TMT) in Participants (pts) with Previously Treated, Advanced KRAS-Mutant NSCLC: Results from Cohort 5d of the SKB264-II-08 Study
Presentation Type: Poster
Presentation #: 1945P
Date and Session Time: October 18, 9:00 AM to 5:00 PM local time

Title: Sacituzumab tirumotecan (sac-TMT) + pembrolizumab[1] (pembro) for treatment-naïve advanced PD-L1 positive NSCLC: results from the Phase 2 MK-2870-003/SKB264-II-04 study
Presentation Type: Poster
Presentation #: 1949P
Date and Session Time: October 18, 9:00 AM to 5:00 PM local time

Title: Sacituzumab tirumotecan (sac-TMT) + Pembrolizumab in Metastatic Castration-Resistant Prostate Cancer (mCRPC): Results from Phase 2 MK-2870-002/SKB264-II-06 Study
Presentation Type: Poster
Presentation #: 2421P
Date and Session Time: October 18, 9:00 AM to 5:00 PM local time

Title: Sacituzumab tirumotecan (Sac-TMT) Monotherapy in Advanced/Metastatic Endometrial Carcinoma (EC): Results from a Phase 1/2 Study (MK-2870-001/KL264-01)
Presentation Type: Poster
Presentation #: 1111P
Date and Session Time: October 18, 9:00 AM to 5:00 PM local time

Title: Efficacy and Safety of sacituzumab tirumotecan (Sac-TMT) Monotherapy in Advanced/Metastatic Cervical Cancer: Results from a Phase 1/2 Study (MK-2870-001/KL264-01)
Presentation Type: Poster
Presentation #: 1168P
Date and Session Time: October 18, 9:00 AM to 5:00 PM local time

About sac-TMT 

Sac-TMT, a core product of the Company, is a novel human TROP2 ADC in which the Company has proprietary intellectual property rights, targeting advanced solid tumors such as NSCLC, BC, gastric cancer (GC), gynecological tumors, among others. Sac-TMT is developed with a novel linker to conjugate the payload, a belotecan-derivative topoisomerase I inhibitor with a drug-to-antibody-ratio (DAR) of 7.4. Sac-TMT specifically recognizes TROP2 on the surface of tumor cells by recombinant anti-TROP2 humanized monoclonal antibodies, which is then endocytosed by tumor cells and releases the payload KL610023 intracellularly. KL610023, as a topoisomerase I inhibitor, induces DNA damage to tumor cells, which in turn leads to cell-cycle arrest and apoptosis. In addition, it also releases KL610023 in the tumor microenvironment. Given that KL610023 is membrane permeable, it can enable a bystander effect, or in other words kill adjacent tumor cells.

In May 2022, the Company licensed the exclusive rights to MSD (the tradename of Merck & Co., Inc., Rahway, NJ, USA) to develop, use, manufacture and commercialize sac-TMT in all territories outside of Greater China (includes Mainland China, Hong Kong, Macau, and Taiwan).

To date, 2 indications for sac-TMT have been approved and marketed in China for the treatment of adult patients with unresectable locally advanced or metastatic triple negative breast cancer (TNBC) who have received at least two prior systemic therapies (at least one of them for advanced or metastatic setting), EGFR mutation-positive locally advanced or metastatic non-squamous NSCLC following progression on EGFR-TKI therapy and platinum-based chemotherapy. In addition, two new indication applications for sac-TMT for the treatment of adult patients with EGFR-mutant locally advanced or metastatic NSCLC who progressed after treatment with EGFR-TKI therapy and with unresectable locally advanced, metastatic hormone receptor positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) BC who have received prior endocrine therapy and other systemic treatments in the advanced or metastatic setting were accepted by the Center for Drug Evaluation of NMPA, and were included in the priority review and approval process. As of today, the Company has initiated 9 registrational clinical studies in China. MSD has initiated 14 ongoing Phase 3 global clinical studies of sac-TMT as a monotherapy or with pembrolizumab or other anti-cancer agents for several types of cancer. These studies are sponsored and led by MSD.

About Trastuzumab Botidotin (A166)

Trastuzumab botidotin is a differentiated HER2 ADC in new drug application (NDA) registration stage to treat advanced HER2+ solid tumors. As an innovative HER2 ADC developed by the Company, it conjugates a novel, MMAF derivative (a highly cytotoxic tubulin inhibitor, Duo-5) via a stable, enzyme-cleavable linker to a HER2 monoclonal antibody with a DAR of 2. Trastuzumab botidotin specifically binds to HER2 on the surface of tumor cells and is internalized by tumor cells, releasing the toxin molecule Duo-5 inside the cell. Duo-5 induces tumor cell cycle arrest in the G2/M phase, leading to tumor cell apoptosis. After targeting HER2, trastuzumab botidotin can also inhibit the HER2 signaling pathway; it has antibody-dependent cell-mediated cytotoxicity (ADCC) activity.

Based on the results of a randomized, controlled, open-label Phase III study, the New Drug Application (NDA) for trastuzumab botidotin was accepted by the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA) in January 2025 for the treatment of adult patients with HER2+ unresectable or metastatic BC who have received at least one prior anti-HER2 therapy was accepted by the CDE of the NMPA. At a pre-specified interim analysis, trastuzumab botidotin monotherapy demonstrated a statistically significant and clinically meaningful improvement in the primary endpoint of progression-free survival (PFS) as assessed by the Blinded Independent Central Review (BICR) compared with T-DM1.

Currently, Kelun-Biotech has initiated an open, multi-center Phase II clinical study of trastuzumab botidotin in the treatment of HER2+ unresectable or metastatic BC that previously received a topoisomerase inhibitor ADC.

About SKB315

SKB315 is a novel CLDN18.2 ADC targeting advanced solid tumors configured with a proprietary, in-house developed humanized CLDN18.2 mAb and a differentiated payload-linker design. Currently, Kelun-Biotech has initiated the exploration in combination with immunotherapy for gastric/gastroesophageal junction cancer (GC/GEJC) while advancing monotherapy studies for tumors expressing CLDN18.2, such as GC/GEJC and pancreatic cancer.

About Kelun-Biotech

Kelun-Biotech (6990.HK) is a holding subsidiary of Kelun Pharmaceutical (002422.SZ), which focuses on the R&D, manufacturing, commercialization and global collaboration of innovative biological drugs and small molecule drugs. The company focuses on major disease areas such as solid tumors, autoimmune, inflammatory, and metabolic diseases, and in establishing a globalized drug development and industrialization platform to address the unmet medical needs in China and the rest of world. The Company is committed to becoming a leading global enterprise in the field of innovative drugs. At present, the Company has more than 30 ongoing key innovative drug projects, of which 3 projects have been approved for marketing, 2 projects are in the NDA stage and more than 10 projects are in the clinical stage. The company has established one of the world's leading proprietary ADC and novel DC platforms, OptiDC™, and has 1 ADC project approved for marketing,1 ADC project in NDA stage and multiple ADC and novel DC assets in clinical or preclinical research stage. For more information, please visit https://kelun-biotech.com/.

CHENGDU, China, Sept. 23, 2025 /PRNewswire/ -- Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. (the "Company") announced that a new drug application (NDA) for the Company's small molecule rearranged during transfection (RET) kinase inhibitor A400 (also known as EP0031) was accepted for review by the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA) of China for the treatment of adult patients with RET-fusion positive locally advanced, or metastatic non-small cell lung cancer (NSCLC). This acceptance for review is based on the positive results from the two pivotal Phase 2 cohorts of the KL400-I/II-01 study for both 1L and 2L+ advanced RET-fusion positive NSCLC.

Cohort 1 and 2, the Phase 2 stage of the KL400-I/II-01 study, evaluate the efficacy and safety of A400/EP0031 90mg orally once daily (QD) for the treatment of patients with pre-treated and treatment-naïve RET-fusion positive locally advanced, or metastatic NSCLC, respectively. Primary efficacy endpoints of the two pivotal cohorts were reached, where A400/EP0031 demonstrated favorable efficacy in pretreated and treatment-naïve NSCLC including patients with prior immunotherapy or brain metastases. A400/EP0031 also demonstrated an encouraging, manageable tolerability and safety profile.

Dr. Michael Ge, CEO of Kelun-Biotech said, "We are pleased to report positive results from the clinical study of A400/EP0031 in treating RET-fusion positive NSCLC, which gives us confidence in its future clinical potential. As a tumor agnostic precision therapy, A400/EP0031 represents our significant strategic positioning in the solid tumor field. We look forward to working closely with regulatory authorities to expedite the review process for A400/EP0031, bringing this innovative therapy to patients with RET-fusion positive NSCLC as soon as possible."

About RET-fusion positive NSCLC

RET gene fusions represent one of the rare yet significant driver mutation types in NSCLC. In Chinese NSCLC patients, the incidence of RET gene fusions ranges from 1.4% to 2.5%[1]. Patients with RET fusions derive limited benefit from conventional treatments. In recent years, the emergence of novel highly selective inhibitors has led to breakthroughs in the clinical management of advanced RET-fusion positive NSCLC patients. However, their therapeutic benefits are limited, in part, by acquired RET drug-resistant mutations and safety issues such as hypertension and hematological toxicity, underscoring the need for novel selective RET inhibitors with improved safety and better efficacy against drug-resistant mutations.

About A400/EP0031

A400/EP0031 is a novel next-generation selective RET inhibitor for NSCLC, medullary thyroid cancer (MTC) and other solid tumors with a high prevalence of RET alterations. The Company is currently conducting a phase 1b/2 clinical study for RET+ MTC and solid tumor in China. The results from the Phase 1 study of A400/EP0031 in patients with advanced RET-mutant MTC were presented at the 2025 ASCO Annual Meeting.

In March 2021, the Company granted Ellipses Pharma Limited, a U.K.-based international oncology drug development company, an exclusive license to develop, manufacture and commercialize this agent outside Greater China and certain Asian countries under the code EP0031.

In March 2024, it was announced that EP0031/A400 was granted Fast Track designation by the Food and Drug Administration (FDA) for the treatment of RET-fusion positive NSCLC. In April 2024, EP0031/A400 was cleared by the FDA to progress into Phase 2 clinical development and is now open in the United States, United Kingdom, Europe and United Arab Emirates.

About Kelun-Biotech

Kelun-Biotech (6990.HK) is a holding subsidiary of Kelun Pharmaceutical (002422.SZ), which focuses on the R&D, manufacturing, commercialization and global collaboration of innovative biological drugs and small molecule drugs. The company focuses on major disease areas such as solid tumors, autoimmune, inflammatory, and metabolic diseases, and in establishing a globalized drug development and industrialization platform to address the unmet medical needs in China and the rest of world. The Company is committed to becoming a leading global enterprise in the field of innovative drugs. At present, the Company has more than 30 ongoing key innovative drug projects, of which 3 projects have been approved for marketing, 2 projects are in the NDA stage and more than 10 projects are in the clinical stage. The company has established one of the world's leading proprietary ADC and novel DC platforms, OptiDC™, and has 1 ADC project approved for marketing, 1 ADC project in NDA stage and multiple ADC and novel DC assets in clinical or preclinical research stage. For more information, please visit https://kelun-biotech.com/

Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. ("Kelun-Biotech", HKEX: 6990) announced that clinical data from a Phase II study evaluating novel TROP2 antibody-drug conjugate (ADC) sacituzumab tirumotecan (sac-TMT) in combination with PD-L1 monoclonal antibody (mAb) tagitanlimab for the first-line treatment of advanced or metastatic non-small cell lung cancer (NSCLC) have been published in Nature Medicine (Impact Factor: 58.7).

The publication highlighted initial findings from the Phase II OptiTROP-Lung01 study, evaluating the efficacy and safety results of sac-TMT in combination with tagitanlimab as a first-line treatment of advanced or metastatic NSCLC patients without actionable genomic alterations. The study was led by Prof. Zhang Li's team at the Center for Cancer Prevention and Control, Sun Yat-sen University, China. Patients in Cohort 1A received sac-TMT (5 mg/kg, Q3W) plus tagitanlimab (1200 mg, Q3W) in a three-week cycle, while patients in Cohort 1B were treated with sac-TMT (5 mg/kg, Q2W) plus tagitanlimab (900 mg, Q2W) in a four-week cycle. Patients received sac-TMT in combination with tagitanlimab in a non-randomized manner until disease progression or unacceptable toxicity. Median follow-ups for Cohort 1A and Cohort 1B were 19.3 months and 13.0 months, respectively (Data cutoff date: May 27, 2024).

The study results demonstrated promising anti-tumor activity, and manageable safety of sac-TMT in combination with tagitanlimab as a first-line treatment for advanced or metastatic NSCLC patients. A total of 40 patients in Cohort 1A and 63 patients in Cohort 1B were included in the full analysis set (FAS) for efficacy assessment. In Cohort 1A and Cohort 1B, respectively, the confirmed objective response rates (ORRs) were 40.0% (95% CI: 24.9–56.7) and 66.7% (95% CI: 53.7–78.0), and the ORRs were:

• 44.4% and 64.7% among patients with non-squamous carcinoma, 36.4% and 69.0% with squamous carcinoma;

• 41.7% and 57.1% among patients with PD-L1 tumor proportion score (TPS) <1%;

• 38.5% and 63.2% for TPS 1–49%;

• 40.0% and 78.3% for TPS ≥50%.

The median progression-free survival (mPFS) for Cohort 1A was 15.4 months (95% CI: 6.7–17.9) and not reached (95% CI: 9.6–NE) for Cohort 1B.

The most common grade ≥3 treatment-related adverse events (TRAEs) for both Cohorts 1A and 1B were decreased neutrophil count, decreased white blood cell count and anemia. No treatment-related deaths were observed.

Subgroup analyses showed consistent efficacy across PD-L1 and TROP2 expression levels, as well as in both squamous and non-squamous histological subtypes.

Dr. Michael Ge, CEO of Kelun-Biotech, commented: "The OptiTROP-Lung01 study supports the promising efficacy and safety of sacituzumab tirumotecan in combination with tagitanlimab as a first-line treatment for patients with advanced NSCLC. The results were observed across PD-L1/TROP2 expression levels and histological subtypes and support the advancement potential of sac-TMT from later-line to front-line therapy. The publication of results from several studies in top-tier international journals reflects the recognition of our innovation-driven development strategy. We will continue to work to address critical clinical challenges and unmet medical needs, striving to deliver more therapeutic options and improve quality of life for patients."

About sac-TMT

Sac-TMT, a core product of the Company, is a novel human TROP2 ADC in which the Company has proprietary intellectual property rights, targeting advanced solid tumors such as NSCLC, breast cancer (BC), gastric cancer (GC), gynecological tumors among others. Sac-TMT is developed with a novel linker to conjugate the payload, a belotecan-derivative topoisomerase I inhibitor with a drug-to-antibody-ratio (DAR) of 7.4. Sac-TMT specifically recognizes TROP2 on the surface of tumor cells by recombinant anti-TROP2 humanized monoclonal antibodies, which is then endocytosed by tumor cells and releases KL610023 intracellularly. KL610023, as a topoisomerase I inhibitor, induces DNA damage to tumor cells, which in turn leads to cell-cycle arrest and apoptosis. In addition, it also releases KL610023 in the tumor microenvironment. Given that KL610023 is membrane permeable, it can enable a bystander effect, or in other words kill adjacent tumor cells.

In May 2022, the Company licensed the exclusive rights to MSD (the tradename of Merck & Co., Inc., Rahway, NJ, USA) to develop, use, manufacture and commercialize sac-TMT in all territories outside of Greater China (includes Mainland China, Hong Kong, Macao, and Taiwan).

To date, two indications for sac-TMT have been approved and marketed in China for the treatment of adult patients with unresectable locally advanced or metastatic TNBC who have received at least two prior systemic therapies (at least one of them for advanced or metastatic setting) and EGFR mutation-positive locally advanced or metastatic non-squamous NSCLC following progression on EGFR-TKI therapy and platinum-based chemotherapy. In addition, two new indication applications for sac-TMT for the treatment of adult patients with EGFR-mutant locally advanced or metastatic NSCLC who progressed after treatment with EGFR-TKI therapy and with unresectable locally advanced, metastatic HR+/HER2- BC who have received prior endocrine therapy and other systemic treatments in the advanced or metastatic setting were accepted by the CDE, and were included in the priority review and approval process. As of today, the Company has initiated 9 registrational clinical studies in China. MSD has initiated 14 ongoing Phase III global clinical studies of sac-TMT as a monotherapy or with pembrolizumab[1] or other agents for several types of cancer. These studies are sponsored and led by MSD.

About Tagitanlimab

Tagitanlimab is the first PD-L1 mAb globally to receive authorization for the first-line treatment of NPC. Previously, the NMPA has approved the marketing in China of tagitanlimab used in combination with cisplatin and gemcitabine for the first-line treatment of patients with R/M NPC and monotherapy for the treatment of patients with recurrent or metastatic NPC who have failed after prior 2L+ chemotherapy, respectively.

About Kelun-Biotech

Kelun-Biotech（6990.HK）is a holding subsidiary of Kelun Pharmaceutical (002422.SZ), which focuses on the R&D, manufacturing, commercialization and global collaboration of innovative biological drugs and small molecule drugs. The company focuses on major disease areas such as solid tumors, autoimmune, inflammatory, and metabolic diseases, and in establishing a globalized drug development and industrialization platform to address the unmet medical needs in China and the rest of world. The Company is committed to becoming a leading global enterprise in the field of innovative drugs. At present, the Company has more than 30 ongoing key innovative drug projects, of which 3 projects have been approved for marketing, 1 project is in the NDA stage and more than 10 projects are in the clinical stage. The company has established one of the world's leading proprietary ADC platforms, OptiDC™, and has 1 ADC project approved for marketing, 1 ADC project in NDA stage and multiple ADC and novel DC assets in clinical or preclinical research stage. For more information, please visit https://kelun-biotech.com/.